This application relates to a unique system for detecting a drowsy driver of a vehicle by using axle sensors to measure and monitor the movements of the vehicle and driving patterns of the driver.
Driver drowsiness often progresses in stages. When a driver first begins to feel sleepy his eyes may involuntarily close or his head may begin to tilt forward or backward for a few seconds. As the driver experiences these initial drowsiness stages, the vehicle may begin to slightly weave back and forth on the road or may slow down and speed up. The driver is usually able to wake himself up in time to regain control of his vehicle before an accident results. As the driver becomes more sleepy, the time intervals that occur between the time when the eyes are closed and when the driver wakes himself up increase in length. This causes the weaving and speed changes to become more pronounced. Eventually the driver becomes so tired that he actually falls into a deeper sleep from which he cannot easily wake himself up. Thus, it is important to be able to detect the initial stages of drowsiness and alert the driver to this condition before the driver falls into this deeper sleep.
Various methods have been used to detect driver drowsiness. These methods can be placed into two basic categories, those methods that monitor the physical movements of the driver himself, and those methods that monitor the movement of certain vehicle components. Methods that utilize monitoring devices for the driver himself include mechanisms that are physically attached to the driver's body to monitor eye movement and the angle of the driver's head. As an example, mechanisms have been proposed which are attached to the vehicle within the passenger compartment and use infrared lens technology to monitor driver eye movement. These mechanisms are not practical. Many of these systems encounter difficulties in adjusting to different driver heights and also have difficulty in adjusting to drivers who assume various seating postures while driving.
Methods that detect drowsiness by monitoring the movement of a vehicle component include methods that monitor steering wheel turn angles. Such methods monitor steering wheel angle changes that occur as the steering wheel is rotated by the driver. Drowsiness is detected when the steering wheel is rotated through a specific set of pre-determined steering angles. These systems are often expensive and require additional hardware to be installed on the vehicle.
Thus, it is desirable to have an inexpensive system for detecting a drowsy driver of a vehicle that utilizes current vehicle components and sensors. It is also desirable to have a system that does not require physical attachment to or monitoring of the driver's body, and which is easily installed and maintained.